PARCHMENT, MI -- Ten years ago, Lydia Chapa and her partner arrived home from the hospital after Chapa's knee surgery to find a child on their porch.

The boy looked familiar. In fact, he looked "identical" to her brother, who had recently died of cancer, Chapa recalled.

The 8-year-old was the brother's son and Lydia Chapa's nephew, dropped off unannounced by relatives who decided they couldn't care for the child anymore. In fact, the boy had been left a few days before and slept under the porch until Chapa and her partner showed up.

"So here was this child," Chapa recalled. "I was like, whoa."

And that's how Lydia became a mother to Andrew Chapa, who graduates next week from Parchment High School.

It wasn't just a turning point for Lydia, who processes insurance claims for State Farm. It also was a major shift in fortunes for Andrew, who spent his first eight years bouncing between his birth mother, his maternal grandmother and his older half sisters.

Those years of instability meant that by the time Andrew landed with Lydia, he had severe behavior issues, an eating disorder and a serious deficiency in academic skills.

"I was a bad little kid," Andrew said.

"Angry," Lydia said. "He had a lot of anger. He had these horrendous tantrums. Taking him out in public was tricky, because you never knew how he was going to act. ... He would lash out at other kids. He was very aggressive and did a lot of off-the-wall things."

It was clear, Lydia said, that Andrew was testing her and "just waiting for the other shoe to drop." He was so used to being rejected that this time, he was doing the rejecting first.

It was a hugely challenging time for Lydia. Caring for a high-maintenance child meant no more skiing trips or vacations to Key West, no more raquetball games with friends.

Even more significantly, Andrew's presence put a severe strain on Lydia's relationship with her partner of 19 years, and the strains increased when Lydia agreed to also take in Andrew's half-sibling, Arius, who is now 14. While Arius was not related to Lydia, "he was Andrew's brother and I couldn't say no to his brother," she said.

Shortly after the Arius moved in, Lydia's partner moved out.

"She had to move on," Lydia said. "It was too hard."

For Andrew, it was a rather stunning development. In his past life when adults had to choose between Andrew and something else, they always choose the other option. But this time, faced with continuing the relationship with her partner or her children, Lydia said, "I told Andrew, 'I choose you.'

"I thought Andrew deserved every opportunity in the world. He didn't deserve another person saying, 'Time to move on,' " she said. "He needed someone to invest in him. Someone had to love him before he loved himself."

Lydia poured herself into getting Andrew on track. She first enrolled him in Kazoo School, where he spent two years in fourth grade.

"Andrew is very intelligent," Lydia said, but before moving in with her, he had been in special education programs. "I think because of his behavior and his background. ... He had no academic skills."

He caught up relatively quickly. After leaving Kazoo School, he was put in the advanced groups at Paramount Charter Academy, where he spent grades 5-8.

The academic piece fell into place quicker than the behavior issues, Lydia and Andrew said. It wasn't until partway through middle school that the behavior problems began to ebb.

"It took a long, long time," Andrew said. "A really long time."

"It took many years," Lydia agreed, and it also took "a village of adults," including teachers, therapists and doctors, not to mention Mary Chapa, Lydia's partner of the past seven years.

But by high school, Andrew hit a sweet spot and he says his years at Parchment have been terrific. He's competed in three sports -- cross country, track and wrestling -- and is graduating with honors, even with taking Advanced Placement calculus and physics.

On June 24, he is headed to San Diego to start basic training for the U.S. Marine Corp. Andrew said he's looking forward to the physical and mental challenge that the Marines will provide and, at this point, he says he may make the military his career.

With his intellectual talents and his physical fitness, Andrew and the Marines are a "perfect match," Lydia says.

"It's been amazing to watch his transformation" over the past decade, Lydia said."I'm very, very proud of him and I'm going to miss him like crazy and he's not even gone yet."

Calling herself "an aunt by blood, a mother by choice," Lydia said that raising Andrew has taken on special significance because of his eerie resemblance to his father, Lydia's deceased brother.

Andrew "looks identical to my brother. It's surreal," she said. "When he first showed up at my house, it was soon after my brother had died and part of me was like, 'What am I going to do with this kid' and part of me welcomed it because I was grateful to have part of my brother."

"I sometimes joke that some people leave their sister a house or money and my brother left me with a child," she said. "But the truth is, it's the best thing he could have left me."